1. Field of the Invention
The present invention relates to an eccentric screw-type pump for pumping products of liquid to pasty consistency, comprising a drive unit that is connected via a driving shaft to a rotor, wherein a first stator and at least one further spare stator are provided.
2. Description of Related Art
An appropriate arrangement of the rotor and the stator or the spare stator, respectively, is disclosed in the German Patent DE 33 45 233 C2. There, an eccentric screw-type pump for pumping liquids from boreholes is used. The eccentric screw-type pumps are located in very substantial depths of up to a few hundreds of meters. As it were very expensive to withdraw the pump from this depth in the case of wear on the stator one or several spare stators are provided that are arranged at mutual distances. The distance between the stators fills the rising pipe. Whenever one or several of the spare stator(s) is employed the linkage is extended or reduced, respectively, in such an application.
The German Patent DE 19 85 861 U discloses a stator for an eccentric screw-type pump, which is composed of two parts. The joints of the two parts are sealed by means of a sealing ring. The rotor extends over both stator parts.
A corresponding arrangement would be too expensive in the conventional eccentric screw-type pumps operated above ground or on the surface and would enlarge the dimensions of the pumps.